Input and output management

Question 1

What are the Categories of i\o devices?

Answer 1

Human Interface(screens keyboards)
Storage Devices(disks tapes)
Transmission devices(Network cards Modem)

Question 2

How can you connect an i\o device ?

Answer 2

Through a port(incresingly rare)

or a bus (increasingly common)

Question 3

What checks the i\o devices activities

Answer 3

Registers

Question 4

What controller registers are there ?

Answer 4

data-in register — data coming from device;
∙ the data-out register — data going to device;
∙ the status register — bits indicating status of device;
∙ the control register — bits giving commands to device.

Question 5

How may controller registers be accessed?

Answer 5

special instructions (increasingly rare) or standard memory instructions (increasingly common)

Question 6

How can a computer approach the i/o devices ?

Answer 6

Polling

Interrupt

Question 7

Is a computer faster or slower than an i\o device

Answer 7

faster

Question 8

How does the polling approach to controling i\o devices work?

Answer 8

The processor checks the

device to see if it is ready.

Question 9

How does the interrupt approach to controling i\o devices work?

Answer 9

The device signals the processor when it is ready

Question 10

Is it better to use polling or interrupts to achieve maximum

processor performance?

Answer 10

Depends

In the case of embedded systems the processor has nothing to so it so its reccomendable to use polling

Question 11

In what case is DMA used ?

Answer 11

When devices that deal with large volumes of data are involved (SSD) .

Question 12

what is DMA for?

Answer 12

For transfering large blocks of data

Question 13

Separate system calls exist for:

Answer 13

character I/O;
block I/O;
memory-mapped I/O;
network I/O.

Question 14

What does a character i\o system call do ? and what are it’s characteristics?

Answer 14

enables an application to get/put
a single character from/to a device
It is low bandwith and straightfoward ()0ususally used foe human interfaces -> intterupt

Question 15

What does a block i\o system call do ?and what are it’s characteristics?

Answer 15

O enable an application to read/write
many characters, and perhaps to seek on a device.
It is used for high volume transfers and for the device to carry on in autonomy

Question 16

What does a Memory Mapped i\o system call do ?and what are it’s characteristics?

Answer 16

It enables an application to

map a device into memory. It’s covenient for a programmer not to deal with the low level processes of a device

Question 17

What does a Network i\o system call do ?and what are it’s characteristics?

Answer 17

It enables an application to
read/write many characters to network device socket. It was designed with a network failure expectation. (interrupt is used as networks work with large amounts of data)